Hi all,I have been thinking for a while for the best (auto)throttle solution for FSBUS. Simply: I want to build a box with throttle control lever which will either be controled from FS (when auto-trhottle is active) or manualy controlled by pilot.How to make ir moving:1) Servo?But: how to get the servo position when in maual mode and how to remove the servo force in manual mode (the servo tries always reach target position and will not allow chamge it manually).2) Stepping motor?Do you know a reliable stepping motor with enough force for reasonable voltage?3) Normal DC motor?How to reach enogh accuracy?And then, how to get the throttle position back to FS? I assume that there will in any case be an analog input used for tracking the throttle lever position.I'd say that the #2 should be the best solution... does anybody have existing and reliable solution?...I mean from electrical (and mechanical) point of view.Thanks for any suggestion!Rada

As for my direct experience (I developed an USB board to drive up to 16 servo motors) best solutions are the #1 and the #2 but they require a different approach.Since servo motors try to hold the target position, the only way to move it manually is to turn off the driving pulse.But you have to consider that a servo can only turn 180

Hi,thanks for your words. I have few 'but's to your message :)Ad servo - as you write it tries to hold the position. However this is not the only problem. Another one is that the speed-change box doesn't like reversed force (from shaft to motor). And another one - I thought that the signal is sent TO the motor logic, not FROM the motor.Simply I think that it makes sense to use servos only for output force, not for input controls.(but this is a knowledge I learned in last few days when I experimented with servos a little bit).On the other side there exist servos used mostly in ship RC models which have higher angle range (e.g. 720

As for servos maybe I explained the concept in a wrong way (english is not my mother tongue so I apologize).Servos are ONLY accepting an input signal that is a PWM signal (as you probably know).If you would use them for your auto throttle, the only way to drive them manually is to turn off servos (with an "auto throttle disengage" button for example).This can be done in two ways: turning off the power supply (VCC) of the servo or cutting off the PWM signal.In both cases a servo stops "reacting".Let's assume that you disengaged the auto throttle (then servos are "sleeping") and you moved your levers leaving unchanged the value of the IAS selector in the autopilot panel: when you engage the auto throttle again, servos will reposition the levers according with the IAS setting of the autopilot panel.So you won't need any potentiometer, A/D conversion etc etc..a servo always knows its position, the only thing that must be done is to give the servo the correct timing of the PWM signal.Of course this is done by FSBUS servo card and, if I'm correct, it positions a servo by sending it a position value between 0 and 255.I think you can easily calculate that value since there is a FSUIPC offset that contains the position of the throttle levers.So your work is just to read that value, convert it to a "255 steps" scale and send the value to the board.I think the thing would be more complex with a stepping motor.Regards and good luck ;)Roberto